If the rumours are true, there may be a new Eminem album before Christmas, the Howard Hughes of hip hop returning from a four-year absence to raise a middle finger to the season of goodwill.

Since the release of Encore in 2004, there has been speculation that Marshall Mathers III, 36, has lost his way - devastated by the murder of his best friend, DeShaun 'Proof' Holton, outside a Detroit club two years ago, and piling on the pounds after a short spell in rehab to fix an addiction to prescription pills. In this last respect, his fate echoes that of Elvis who, like Eminem, was simplistically accused of stealing black music and making it palatable to a white audience (and never mind that that achievement alone tacitly posits a degree of genius). Intense scrutiny awaits this comeback, even though the peroxide-blond rapper with the acid tongue will be re-emerging into a different cultural milieu.

First, however, comes The Way I Am, which is essentially the Eminem story in coffee-table-friendly format. It is light on text (and that which there is is based on a series of interviews with writer Sacha Jenkins) and heavy on imagery. There are more than 250 photographs, including artfully staged shots of Eminem the street poet, and a number of Polaroids (Em with Hugh Hefner, with Dustin Hoffman, with Robin Williams - raising the question of whom the joke might be on). There is, inevitably, a spread devoted to his collection of custom-made sneakers; there are examples of his own artwork - drawings of superheroes alongside his own heroes, such as Tupac Shakur; and also shots of crumpled lyric sheets, which are probably of considerable interest to Seamus Heaney, who is quoted approvingly on the jacket thus: 'There is this guy Eminem. He has created a sense of what is possible. He has sent a voltage around a generation.'

It shouldn't surprise the Nobel laureate that the rapper's story is better told through his lyrics than through words and pictures. The confessional culture that served up Oprah Winfrey and Jerry Springer on TV found its rap counterpart with Eminem who, with devastating forensic skill, picked over his troubled upbringing and the state of his relationship with ex-wife Kim and his litigious mother Debbie in his songs. The book treads lightly here and also skirts the issue of his addiction ('The whole drug thing built into a problem for me at some point,' he writes. 'I'm glad I realised it and set myself in the right direction'). The most illuminating bits are the family snapshots, such as portraits of Mathers's uncles Todd and Ronnie Nelson (both of whom committed suicide) and an uncomfortable image of his father holding him as a baby, shortly before Marshall Bruce Mathers Jr abandoned the family. This is the only photograph of his father that Marshall III ever saw as a child.

Publication of Eminem's book coincides with that of Cobain Unseen, an equally lavish collection of private photographs of that other helpful archetype. The Detroit rapper became hip hop's posterboy in suburban white America because he spoke to the same generational malaise as Kurt Cobain, who came from a similarly broken home. Both were reluctant superstars, but the Nirvana singer turned the angst that he'd identified in on himself - leading to his suicide, and his dismissal by Liam Gallagher (at a time when Britpop was in the ascendant in Britain and Blair was on the way) as a 'sad cunt who couldn't handle the fame'.

It was easier for Marshall Mathers because of the tool-kit with which hip hop supplied him: rather than fret about issues of authenticity, the rapper delved into cartoon-like levels of misogyny and violence, able to hide behind his Eminem and Slim Shady alter egos, laughing (it is always tempting to underestimate the role of humour in hip hop) at the idea that he might occasion moral panic. But a track such as 'White America', from his fourth album, The Eminem Show, where he spat about: 'So many lives I touch, so much anger aimed in no particular direction, just sprays and sprays/ Straight through your radio waves it plays and plays', spoke the truth about a sector of American society. It is that same constituency so traduced by the sickeningly cheery Sarah Palin as 'proud valley trash'.

Since his self-imposed absence from the pop arena, hip hop has changed both musically and because rappers such as Kanye West are more in tune with the aspirational narrative of Barack Obama's America (if not actually claiming a part in scripting that narrative themselves). Eminem's forthcoming album has been trailed by the curiously low-key single 'I'm Having a Relapse' (that familiar chainsaw sound notwithstanding), and the expectations raised by a characteristically pithy extended picture caption here are slight: 'I've been having a hard time recording since Proof died. I've got hundreds of songs, though. Stuff that I just make for my own amusement - material just for me, and only me.' But whatever emerges is bound to be more revealing than this book - the tone of which is caught curiously between celebration and disaffection - and there is certainly a silent fanbase waiting to be mobilised by Eminem's return.